BUILDINGS - Smarter Facilities Management

03/28/2016

LED Upgrades for Fluorescent Tubes

Snap-in designs cut installation cost for office and high-bay applications

By Eric Woodroof, Ph.D., CEM, CRM

 
LED lights

I am a big fan of LEDs. They are energy-efficient and have a long service life. They are ballast-free, which removes a potential point of failure and a consumer of energy.

However, I have not always been sold on replacing fluorescent tubes with LED tubes due to the high material cost, as much as $50 each. The incremental benefit (fewer watts consumed) was not enough to overcome the incremental cost. For clients with low operating hours and/or low energy costs (10 cents/kWh), I had been playing it safe by retrofitting T-12 systems with T-8s or T-5s. The results were very predictable.  

Two factors have changed my view. One, the cost of LED lamps continues to fall. Second, a snap-in LED design simplifies installation, further reducing costs. These LED tubes look a little like light sabers from Star Wars movies because they do not have pins on their ends, unlike fluorescent lamps and other LED tubes. They have one flat side with two magnets to snap the lamp into place in a ceiling fixture, where it can be wired directly to line voltage. They do not need any lamp holders (aka tombstones), thus removing another potential point of failure since old plastic lamp holders often break during installation of new lamps.

Each of the following two case studies includes a cost breakdown. While the energy savings are significant, remember that the quality and level of lighting are also critical. Do a test of any proposed relamping project to ensure that occupants will embrace the results.

You can view an 8-minute video with more information on these two case studies at www.profitablegreensolutions.com/content/ballast-free-led-retrofits.

Case Study 1: Bank Office Retrofit

My client had 2-foot by 4-foot T-12 recessed fixtures with four lamps behind a lens (see photo 1). Because these lamps were phased out of production in 2014, the client had to make a change.

My routine retrofit would replace the four lamps and two T-12 magnetic ballasts with two new T-8 or T-5 lamps and one ballast (see photo 2). I tested sample fixtures with T-8s in the client’s office. Then, out of curiosity, I also installed a fixture with $25 snap-in LED strips next to the other test fixtures (photo 3).

Ultimately I chose the LEDs for the client’s project. Lighting levels and light quality were improved and energy cut by 65–70%. Although the facility’s operating hours totaled only 2,000 hours per year, the LEDs had a good payback. (See costs at right.)

This LED retrofit doesn’t require recycling of the old sockets, which may be near the end of their useful life anyway. You also don’t need to fit new lamp holders into your old metal fixture since the LED tubes don’t have the two pins at each end. The small magnets on the back of the LED attach easily to the back of the fixture. Installation labor was less because this retrofit had only five steps:

New two-lamp T-8 fixture with reflector

1) Open lens  
2) Cut all the wires
3) Remove the ballasts and lamps
4) Snap in the two LED tubes
5) Hardwire the tubes and close the lens

That’s it! In the now vacant space where the T-12 ballasts were attached, I had ample room to contain the wire connections and wire nuts to satisfy our local electrical code.

Aesthetics, Risks and Downsides

For this project, most occupants preferred reading under the LED fixture, probably because the color rendering index was higher (80 CRI) than that of the existing fluorescents (70 CRI).  

Many LED strips/tubes come with either a frosted shield or clear plastic. Frosted is best if the strip/tube is visible to the occupants because it reduces the glare and the ability for someone to see the LED sources, which can be too bright for many people. The clear lens is useful for indirect lighting, when the light source is shielded from occupant view.

LEDs are basically tiny computers that are more sensitive to voltage or current fluctuations than fluorescent lamps. During testing, look for flicker when refrigerators, laser printers and other large devices turn on.

New LED tubes

These LEDs had a five-year, unconditional warranty. When they fail, my client will need to replace two $25 LED tubes instead of two $2 fluorescent lamps. However, if the retrofit economics are favorable today, they should be even more so in the future because LED manufacturing costs are falling rapidly.  

COST BREAKDOWN

Existing fixture energy input: 144 watts per four-lamp fixture
LED fixture energy input: 18 watts per two-lamp fixture
LED tube material cost: $25 each
LED installation cost: $15 per fixture
Fixture rebate from local utility (your rebate may vary): $11

Savings per fixture
= [(144 watts/fixture) – (36 watts/fixture)] x 2,000 hours/year
= 216 kWh/year, which equals about $21.60 per year per fixture
in energy savings @ 10 cents/kWh

When projecting your savings from a retrofit, you may want to include savings from reduced labor and HVAC load. But as you can see below, the payback is impressive without these factors.

Installation costs per fixture
= [($25/tube) x (2 tubes)] + ($15 installation) – ($11 rebate)
= $54 per fixture

Simple payback
= ($54/fixture)/($21.60/year in savings)
= 2.5 years


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